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Öğe Changes in milk fatty acid composition of goats during lactation in a semi-intensive production system(Archiv Fur Tierzucht, 2009) Ataşoğlu, Cengiz; Uysal Pala, Çiğdem; Karagül Yüceer, YoncaThis study aimed at investigating changes in the fatty acid (FA) profile and conjugated linoleic acid (CLA) concentration of milk fat during lactation from goats managed in a semi-intensive production system, which consisted of grazing on a woody and herbaceous pasture with the supplementation of mixed concentrate and vetch hay. A total of 21 lactating goats were used. Milk samples were collected at different periods (25 April, 29 June, 25 August and 4 October) during lactation and analysed for their chemical composition and FA profile. The most abundant FA in the milk fat of goats was palmitic (06:0) acid, followed by oleic (C18:1 n-9), stearic (C18:0), capric (C10:0) and myristic (04:0) acids. These acids accounted for about 88% of the total milk FA of goats in all sampling periods. The two medium chain FA; capric (P=0.0001) and lauric (C12:0; P=0.0014) acid were affected by the sampling period, whereas myristic (P=0.4469) and palmitic (P=0.4418) acids did not change. Stearic (P=0.0128), oleic (P=0.0001), linoleic (C18:2; P=0.0088) and linolenic (C18:3; P=0.0001) acids also exhibited significant variations between the sampling periods. However, the CLA (C18:2 c9, t11 and C18:2 00, c12) contents of milk fat did not change during the entire study regardless of the sampling period (P=0.2448). Milk fatty acid composition of goats, which meet a major part of their nutrient requirements through grazing or browsing in a natural pasture, shows a seasonal variation with milk fat in summer representing a better fatty acid profile for product quality.Öğe Chemical, microbial, and volatile changes of water kefir during fermentation with economic substrates(Springer Science and Business Media Deutschland GmbH, 2023) Gökırmaklı, Çağlar; Karagül Yüceer, Yonca; Güzel-Seydim, Zeynep BanuWater kefir is a plant-based type of kefir and has significant differences from well-known milk kefir. Recently, various complicated substrates were fermented with water kefir grains, but an economical substrate is essential for the industrial aspect. This study aims to understand changes in fermentation products of water kefir grains during fermentation with economic substrates and investigates how fermentation progresses under almost ideal fermentation parameters. The fig-based medium provided high contents of Lactobacillus spp. and Lactococcus spp. Also, fig-based medium with high fructose content contained a higher amount of Bifidobacterium sp. Moreover, the fig-based medium resulted in more organic acid content, forming as much as ten times higher than the sugar-based medium for lactic acid after the same fermentation time (p < 0.05). On the other hand, volatile compounds such as acetaldehyde, ethyl acetate, ethanol, acetic acid, 2-ethyl-1-hexanol, oxime-, methoxy-phenyl, and phenylethyl alcohol were detected for both water kefir samples. Antioxidant capacity (TEAC and ORAC) was higher for the fig-based medium than for the sugar-based medium. This is the first study that comprehensively proved that only sugar solution was not a sufficient medium for water kefir fermentation, but fig containing solution had abundant nutrients to obtain preferable and acceptable water kefir beverage.Öğe Effects of heat treatment, plant coagulant, and starter culture on sensory characteristics and volatile compounds of goat cheese(Elsevier Inc., 2023) Uzkuç, Hasan; Karagül Yüceer, YoncaThe effects of heat treatment, coagulant source, and starter culture addition on the physicochemical, sensory characteristics, and volatile compounds of goat cheese were evaluated. For this purpose, the goat cheese was produced from raw milk or heat-treated milk coagulated with Cynara cardunculus L. protease or calf rennet. The effect of the starter culture addition was also investigated. No significant differences were observed between the cheeses produced using different coagulants in terms of chemical, microbiological and sensory parameters, and proteolysis levels, but the combination of heat treatment and starter culture addition affected most of the attributes. A total of 27 volatile compounds, including acids, alcohols, esters, ketones, and aldehydes, were identified in the cheeses during ripening. Acidic compounds were the most abundant volatiles in cheeses. The raw milk cheeses had the highest sensory scores, while an unpleasantly bitter taste was recorded for the heat-treated and starter-free milk cheeses.Öğe MİKRODALGA DESTEKLİ HİDRODİSTİLASYON YÖNTEMİYLE ELDE EDİLEN PELARGONIUM GRAVEOLENS (ITIR) ESANSİYEL YAĞININ KARAKTERİSTİK BAZI ÖZELLİKLERİ(Gıda Teknolojisi Derneği, 2021) Aydınlık, Pelin; Karagül Yüceer, YoncaBu çalışmada Pelargonium graveolens’den (ıtır) elde edilen esansiyel yağın karakteristik özellikleri incelenerek doğal katkı maddesi olarak elma suyunda kullanılabilirliği araştırılmıştır. Esansiyel yağ üretiminde mikrodalga destekli hidrodistilasyon yöntemi kullanılmış ve %1.75 verimle esansiyel yağ üretimi gerçekleştirilmiştir. Uçucu bileşenlerin tanımlanması amacıyla gaz kromatografisi kütle spektrometresi kullanılmıştır. Itır esansiyel yağının temel uçucu bileşenleri sitronelil format, izomenton, linalol, sitronelol ve geraniol olarak belirlenmiştir. Esansiyel yağın antioksidan aktivitesi 0.54 mM troloks/mL yağ bulunmuştur. Esansiyel yağın antibakteriyel etkisinin Escherichia coli’ye kıyasla Staphylococcus aureus üzerine daha fazla olduğu saptanmıştır. Itır esansiyel yağı ilave edilmiş elma suyunun mikrobiyel yükünde depolama boyunca düşüş olduğu belirlenmiştir. Ayrıca esansiyel yağ ilave edilen elma suyunun duyusal özellikler bakımından da kabul edilebilir olduğu tüketici testiyle ortaya koyulmuştur.Öğe Near- and mid-infrared determination of some quality parameters of cheese manufactured from the mixture of different milk species(Springer, 2021) Ayvaz, Hüseyin; Mortas, Mustafa; Doğan, Muhammed Ali; Atan, Mustafa; Yıldız Tiryaki, Gülgün; Karagül Yüceer, YoncaThis study aimed to evaluate the performance of both near-infrared (NIR) diffuse reflectance and mid-infrared-attenuated total reflectance (MIR-ATR) in determining some quality parameters of a commercial white cheese made of unknown ratios of various milk species. For this purpose, 81 commercial Ezine cheese samples, a special ripened cheese produced in Turkey, containing unknown ratios of bovine, caprine, and ovine milk, were used. Reference analyses, including textural properties, protein content, nitrogen fractions, ripening index coefficients, fat, salt, dry matter-moisture, and ash contents as well as pH and titratable acidity levels, were conducted in the samples following the traditional gold standards. For NIR applications, the spectra of both intact cubes and hand-crushed cheese samples were collected, whereas the spectra of only hand-crushed cheese samples were collected for MIR-ATR. PLSR (Partial Least Squares Regression) calibration models were developed for each parameter (n = 61) and then validated using both cross-validation (leave-one-out approach) and an external validation set (n = 20). Overall, PLSR models developed for total protein, fat, salt, dry matter, moisture, and ash content, as well as pH and titratable acidity, yielded satisfactory performance statistics in the complementary use of NIR and MIR spectroscopy. However, PLSR models of the other parameters, including textural properties, nitrogen fractions, and the ripening index, could only separate high and low values and were not able to make accurate quantitative predictions. NIR spectroscopy was found to be more accurate than that of MIR-ATR spectroscopy for almost all the parameters except for pH and titratable acidity, for which MIR-ATR spectroscopy was superior.Öğe Sensory characteristics of Ezine cheese(Wiley, 2007) Karagül Yüceer, Yonca; İşleten, Müge; Uysal Pala, ÇiğdemEzine cheese is a full-fat, white pickled cheese ripened in tinplate containers. A mixture of milks from goat, sheep and cow is used to make Ezine cheese. It has its own characteristic taste and aroma that differ from other white cheeses. In this study, the chemical composition and sensory attributes of Ezine cheese were characterized. A descriptive sensory evaluation technique was used to determine flavor and texture characteristics. Representative Ezine cheeses (22) were provided by local producers. A highly trained (n = 9) panel generated the descriptive terms and identified the references. Fourteen flavors and 10 texture terms were developed to describe Ezine cheese flavor and texture. Some characteristic flavor and taste descriptors for Ezine cheese were free fatty acids, cooked, creamy, whey-like, goaty, salty and sour. Cheese texture was evaluated using hand, mouth and residual techniques. Texture analysis indicated that Ezine cheese had soft and semi-hard texture properties. In general, most of the Ezine cheeses showed similarities in terms of hand firmness, mouth firmness, fracturability and number of particles attributes.Öğe Sensory properties of drinkable yogurt made from milk of different goat breeds(Wiley, 2006) Uysal Pala, Çiğdem; Karagül Yüceer, Yonca; Pala, A.; Savaş, TürkerDrinkable yogurts made from different goat breed milk and made with normal and probiotic cultures were evaluated for their sensory characteristics. Milk of Turkish Saanen, Maltese and Turkish Hair goats obtained during the beginning, middle and end of lactations were used to produce drinkable yogurt. Using descriptive sensory analysis technique, common terms were developed as goaty, creamy, fermented, cooked, throat burn, sweet, salty, sour and astringent. Breeds, lactation periods and using regular and probiotic types of starter cultures affected the sensory characteristics of drinkable yogurts. Drinkable yogurts made by cow milk had weaker intensities of flavor attributes including goaty, creamy, throat burn and salty than that made by goat milks of the three breeds. Drinkable yogurts made from Turkish Saanen breed had more goaty flavor than those made from Turkish Hair and Maltese goat breeds. The products made by milk provided at the end of lactation period had the highest intensities of goaty flavor. In addition, the intensities of goaty, creamy and cooked flavors in the products made by regular yogurt cultures were higher than those of drinkable yogurts with probiotic cultures.Öğe Stabilisation of lavender essential oil extracted by microwave-assisted hydrodistillation: Characteristics of starch and soy protein-based microemulsions(Elsevier B.V., 2021) Çelebi Uzkuç, Nesrin Merve; Uzkuç, Hasan; Berber, Mehmet Mert; Tarhan Kuzu, Kübra; Togay, Sine Özmen; Kırca Toklucu, Ayşegül; Kurt, Saliha B.; Şahiner, Nurettin; Karagül Yüceer, YoncaIn this work, microwave-assisted hydrodistillation (MAHD) technique was used to obtain lavender essential oil (LEO) with a yield of 5.5 %. Oil in water microemulsions of LEO were prepared with starch and soy protein by ultrasonic emulsification. Total phenolic content and antioxidant capacity of the samples were evaluated. Microemulsions exhibited antimicrobial effect against S. aureus and B. cereus. The major volatiles of LEO were linalool L (29.0 %), 1,8-cineole (13.9 %), camphor (12.3 %) and linalyl acetate (11.9 %). Camphene, 1,8-cineole, (Z)-ocimene, linalool, and 2,6-nonadienal were determined as aroma-active compounds by gas chromatography-olfactometry. The stability of emulsions at different pH (3, 6 and 9) and temperatures (4 and 25 °C) were evaluated by measuring their size distribution, zeta potential, viscosity and color during storage. The stable droplets of LEO microemulsion that ranged between 392 and 732 nm were obtained with starch at pH 6. The formulated starch-based emulsions of LEO at pH 6 revealed the highest stability at 25 °C.Öğe TİRE ÇAMUR PEYNİRİNİN BAZI FİZİKOKİMYASAL VE DUYUSAL ÖZELLİKLERİ(2021) Karaalioğlu, Onur; Günay, Ezgi; Karagül Yüceer, YoncaBu çalışmanın amacı, İzmir’in Tire ilçesinde geleneksel olarak üretimi gerçekleştirilen Tire Çamur peyniri’nin bazı fizikokimyasal ve duyusal özelliklerinin belirlenmesidir. Bu çalışma kapsamında analizleri gerçekleştirilen Tire Çamur peyniri örnekleri arasında bileşim bakımından önemli farklılıklar olduğu saptanmıştır. Gaz kromatografisi-kütle spektrometrisi (GC-MS) vasıtasıyla gerçekleştirilen kromatografik analizlerde toplam 29 adet uçucu bileşen tespit edilmiştir. Duyusal değerlendirmeler sonucunda ise pişmiş, peynir altı suyu, kremamsı, fermente ve sütümsü yoğun olarak algılanan aromatikler olarak belirlenmiştir. Elde edilen veriler kapsamında, ürünün endüstriyel boyutlarda üretim standardizasyonunun sağlanmasıyla birlikte tüketiciler için ürünün kaynağını gösteren coğrafi işaret alınmasının; üreticiye, üretildiği bölgeye ve ülkemize önemli ekonomik katkı ve katma değer sağlama potansiyeline sahip olacağı düşünülmüştür.Öğe Yayıkaltı içeceğinin fizikokimyasal ve duyusal özellikleri ile uçucu bileşenlerinin belirlenmesi(2021) Öğe, Çisem; Karagül Yüceer, YoncaBu çalışmada yayıkaltı suyunun farklı mikroorganizmalarla fermantasyonu ile üretilen içeceklerin karakteristik bazı özelliklerinin belirlenmesi amaçlanmıştır. Toz halindeki yayıkaltının %10’luk çözeltisi ile belirli oranlarda (% 0, 25, 50, 75, 100) çiğ süt karışımına ısıl işlem uygulandıktan sonra örneklere L. acidophilus (LA) kültürü ve L. acidophilus, Bifidobacteria ile S. thermophilus karışık kültürü (ABT) ilave edilerek 37°C’de, yaklaşık 4.8 pH’ya kadar inkübe edilmiştir. Ürünlerin fizikokimyasal ve duyusal özellikleri ve uçucu bileşenleri depolama süresince belirlenmiştir. İçeceklerde yayıkaltı suyu oranı azaldıkça yağ, kurumadde ve protein oranları artmıştır. Örneklerde uçucu bileşenler gaz kromatografisi kütle spektrometrisi kullanılarak belirlenmiştir. Tüm örneklerde belirlenen uçucu bileşikler aseton, 2,3-butandion, asetoin, toluen, 2-heptanon, limonen, ökaliptol, asetik asit ve butanoik asit olmuştur. Yayıkaltı içeceklerinde pişmiş, kremamsı, süthane/sütümsü, fermente, karton, yosun, sabunsu, depo, tatlı, tuzlu, buruk ve acı terimleri duyusal değerlendirmeler sonucunda belirlenmiştir.
